1. Field of the Invention
The present invention relates to a folding knife having a handle which is elongate in a main direction, at least one blade mounted so that it can pivot on the handle between a position in which it is at least partially retracted into the handle and an open work position, and a member for locking the blade in the open position.
2. Description of the Related Art
Many knives of this kind are known in the state of the art under the general term of xe2x80x9cflick knifexe2x80x9d.
They are often relatively complicated to manufacture given the various members needed to perform the aforementioned functions. The complexity of the design is further exacerbated in the case of two-bladed folding knives, such as electricians"" knives, in which one blade is designed to cut through a cable and the other blade is designed to be used for cable-stripping operations.
A main object of the invention is to produce a folding knife of the type described above, and in which the open position is stable and defined positively to guarantee longitudinal and circular cuts in complete safety.
To this end, in the open position, the blade makes an angle with respect to the main direction of the handle appreciably greater than 10xc2x0 and appreciably smaller than 90xc2x0, and preferably 40xc2x0.
According to other features:
the blade has a length of between 30 mm and 55 mm and in particular roughly equal to 45 mm;
the blade has a concave cutting edge, the mean radius of curvature of which is between 40 mm and 60 mm, particularly roughly equal to 50 mm;
the knife has two pivoting blades of different lengths, the first blade having a length greater than the length of the second blade, each of the blades making a respective acute angle with respect to the main direction of the handle, the angle associated with the second blade being greater than the angle associated with the first blade, appreciably greater than 10xc2x0 and appreciably smaller than 90xc2x0, and preferably between 20xc2x0 and 60xc2x0, and preferably roughly equal to 40xc2x0; and
the knife has two pivoting blades of different lengths, each having a concave cutting edge with a respective curvature which is different for each blade, and each making a respective acute angle with respect to the main direction of the handle, one of the blades being associated both with the larger of the two angles and the larger of the two curvatures.
Another main object of the invention is to produce a folding knife of the aforementioned type, further comprising a member for actuating the locking member to switch the member from a locking position to an unlocked position, and a member for returning the locking member to the locking position, which is less expensive to manufacture and extremely reliable.
To this end, the actuating member and the return member are formed on a single operating piece mounted on the handle.
According to other features:
the operating piece is a lever mounted so that it can pivot on the handle about a pin that is transverse with respect to the main direction;
the blade has a notch and the locking member has a projection that complements the notch, formed on the lever;
the blade has an edge forming a cam near the notch, the cam collaborating with the projection between the retracted position and the open position of the blade;
the lever is partially retracted into the handle, and the actuating member projects from the handle on the opposite side of the lever from the locking projection with respect to the pivot pin of the lever;
the lever has three branches arranged roughly in a Y-configuration in a longitudinal plane of the handle, and its pivot pin lies roughly at the region where the three branches meet, two of the three branches supporting, respectively, the locking member and the actuating member, while the other branch constitutes the return member;
the handle is secured to at least one transverse relief and the branch constituting the return member has a free end part which bears on the relief so that pressure exerted on the actuating member causes elastic deformation of the branch and generates an elastic return force on the lever, returning it towards a position of rest of the lever;
when the lever is in the position of rest, either the blade is in its open position and the projection is engaged in the notch, or the blade is in the retracted position in the handle and the projection rests against the cam, creating a force on the blade that opposes the opening thereof;
the cam and the projection are configured in such a way that the elastic action of the lever on the blade tends to bring the blade into one or other of its positions: open and retracted;
the knife has two blades each associated with an operating piece, and which pivot with respect to the handle about a common pivot pin; and
the two blades are associated with a common operating piece formed between them in the handle.